1. Field of the Invention
The present invention relates generally to a mounting arrangement for an automotive power unit and more specifically to such a mounting arrangement which utilizes electrorheopectic fluid-filled bushes and which features control by a remotely mounted vibration sensor or sensors.
2. Description of the Prior Art
JP-A-60-104828 discloses a previously proposed engine mount which includes a main working chamber the volume of which varies with the distortion of an elastomeric member which defines a part of the same and which acts as a spring. The main working chamber communicates with a variable volume auxiliary chamber via an orifice passage. The main and auxiliary chambers are filled with an ERF and the orifice passage lined with electrodes by which the viscosity of the ERF contained therein can be controlled.
A similar type of arrangement is disclosed in U.S. Pat. No. 4,928,935 issued on May 29, 1990 in the name of Matsui. The aim of this type of arrangement is to provide relatively long orifice passages between the working chamber and an expansion chamber in which the slugs of ERF can be induced to undergo resonance in the absence of any voltage impression on the electrodes disposed therein, and in response to vibration such as generated during engine idling. This arrangement allows the dynamic spring constant of the mount to be reduced in a manner which enables the transmission of vibration from the power unit to the vehicle chassis to be greatly attenuated. By selectively impressing a voltage on the electrodes disposed in the above mentioned "long" orifice passages it is possible to vary the dynamic spring constant of the mount in a manner which enables different frequency vibrations to be damped.
While the above described devices have proven relatively effective, an automotive power unit is inevitably supported by a plurality of mounts and it is not always possible to effectively damp the transmission of engine vibration to the vehicle chassis simply by varying the dynamic spring constant in accordance with a parameter indicative of the frequency of the vibration which is being produced by the engine.